What Is Warmup Deliverability and How Is It Calculated?

Warmup deliverability is a critical measure of how well your email account performs during the warmup phase — the period when you gradually start sending emails from a new or previously inactive (cold) email account to build a good sender reputation. It indicates the percentage of your warmup emails that are successfully delivered to the recipient’s primary inbox rather than being blocked or sent to spam.

What Is Warmup Deliverability?

Warmup deliverability measures the effectiveness of your email warmup process by tracking how many of your sent warmup emails are accepted by recipient mail servers and actually land in inboxes (primary or promotional folders). A high warmup deliverability means your emails are considered trustworthy by receiving servers, improving your sender reputation and reducing the chances of being flagged as spam.

Why Warmup Deliverability Matters

• Builds sender reputation safely: Gradual positive signals tell email providers your address is legitimate.

• Prevents spam folder placement: Higher deliverability means fewer emails get filtered as spam.

• Prepares for campaign success: With stable warmup deliverability, you gain confidence to start larger email outreach.

• Avoids blacklisting: Proper warmup helps reduce spam complaints and bounces that harm your domain or IP reputation.

How Is Warmup Deliverability Calculated?

Warmup deliverability is calculated as the percentage of warmup emails landing in the primary inbox or accepted by the recipient servers out of the total warmup emails sent.

Calculation Formula

Example: If your email account sent 100 warmup emails and 70 of them landed in the primary inbox while 30 landed in spam or were blocked, your warmup deliverability rate would be 70%

Key Components Affecting Warmup Deliverability

• Inbox Placement Rate: Percentage of emails reaching the main inbox versus spam or promotions.

• Bounce Rate: High bounce rates due to invalid addresses reduce deliverability.

• Spam Complaints: Emails marked as spam lower your sender reputation.

• Technical Setup: Proper SPF, DKIM, and DMARC records improve trust with recipient servers.

• Engagement Signals: Replies, opens, and positive interactions enhance your reputation.

How MailOptimal Tracks and Reports Warmup Deliverability

MailOptimal continuously monitors your warmup deliverability by:

• Comparing total warmup emails sent versus those accepted by recipient servers.

• Tracking where your emails land: primary inbox, promotions, or spam folders.

• Displaying real-time deliverability percentages on your warmup dashboard.

• Sending alerts and recommendations if deliverability drops, so you can tweak settings or fix technical issues.

Best Practices to Maximize Warmup Deliverability

• Gradually increase your email volume; avoid sudden spikes.

• Clean your contact lists to reduce bounces and complaints.

• Ensure your domain authentication (SPF, DKIM, DMARC) is correctly configured.

• Encourage natural engagement through automated warmup replies.

• Regularly monitor warmup deliverability metrics and address any warnings promptly.

Summary Table: Warmup Deliverability Metrics

By understanding and monitoring your warmup deliverability, you can ensure your email warmup process in MailOptimal builds a strong reputation foundation. This prepares your email account for successful outreach and consistent inbox placement essential for your campaigns to reach the right audience effectively.

For detailed analytics and guidance, use your MailOptimal dashboard to track your warmup deliverability trends and optimize your email sending strategy continuously.